Petrochemicals are used in the manufacture of:

Options

A. polythene
B. detergents
C. fibres
D. all of these

Explanation

### Step-by-Step Solution:

1. **Understanding Petrochemicals**:
- Petrochemicals are chemical products derived from petroleum. They are obtained during the refining process of crude oil.

2. **Identifying Major Petrochemicals**:
- One of the major petrochemicals is ethylene. Ethylene can undergo polymerization, which is a chemical process that combines small molecules (monomers) into a larger molecule (polymer).

3. **Manufacture of Polythene**:
- When ethylene is polymerized, it forms polythene (polyethylene), which is a widely used plastic. Therefore, petrochemicals are indeed used in the manufacture of polythene.

4. **Detergents**:
- Alcohols, which are also derived from petrochemicals, are key ingredients in many detergents. This indicates that petrochemicals are used in the production of detergents as well.

5. **Fibers**:
- Aromatic petrochemicals can be used to manufacture synthetic fibers. These fibers are used in various textiles and materials. Thus, petrochemicals play a role in the manufacture of fibers.

6. **Conclusion**:
- In summary, petrochemicals are used in the manufacture of polythene, detergents, and fibers.

### Final Answer:
Petrochemicals are used in the manufacture of:
- Polythene
- Detergents
- Fibers